The present invention relates to a saw and saw blade for simultaneously cutting and beveling, and specifically to a handheld saw with a blade for simultaneously cutting and beveling pipe.
A standard water main pipe used in underground water systems generally has a "straight" end and a "bell" end. The pipe is sealed by plugging the straight end of one pipe into the bell end of the next pipe or part in the system. Inside the bell end is a lip seal that the pipe slides through so as to form the water seal. The pipe is produced in standard lengths with a mill or beveled edge on the straight end to allow it to slide past the seal in the bell end without damaging it. Often the standard length pipe often must be shortened, for example, to fit into a joint or elbow to go around a corner, however, after the pipe is cut, it no longer has the factory mill.
One method currently used for cutting and milling pipe uses a standard cut-off saw to cut the pipe as the pipe is rolled a first time and then uses a standard hand grinder to put a mill on the pipe as the pipe is rolled a second time. This two tool method is time consuming, requires the use of two separate tools, and requires that the pipe must be rolled twice.
Another method currently used for cutting and milling pipe uses a standard cut-off saw to cut the pipe as the pipe is rolled a first time and then uses the same cut-off saw to put a mill on the pipe as the pipe is rolled a second time. This second method is not approved by OSHA and produces a sand paper finish. A sand paper finish is not suitable for some applications. Like the two tool method, this method requires that the pipe be rolled twice, once to cut it and once again to mill it. Also, this method is particularly time consuming and produces poor quality results.
Reed Manufacturing Company produces universal pipe cutters (UPC). Universal pipe cutters are popular because, by choosing the proper blade, they are capable of cutting a pipes made from a wide variety different materials including PVC, PE, cast iron, ductile iron, and vitreous clay. Also, the universal pipe cutters can be used in many locations including above ground, below ground such as in a ditch, and under water. Further, only one revolution is to cut most types of pipes. However, operating these universal pipe cutters is far from simple. Some of the operational steps include wrapping a chain around the pipe to secure the cutter to the pipe, connecting the chain, tightening a turnbuckle, attaching a power source, feeding a blade, and pulling the cutting apparatus clockwise around the pipe. Another problem with Reed's universal pipe cutters is the large quantity of equipment and accessories necessary to cut a pipe. For example, in addition to the blade and cutter, a Reed universal pipe cutter would need a chain with a turnbuckle, an air or hydraulic driven motor with a hose system, a filter, a regulator, a lubricator, a water tank with a cart, a hex key set, oil and/or grease, metal wedges, and a set of wrenches. Further, setting up this system is relatively complicated and time consuming.
One blade available for use with the Reed universal pipe cutters can be used to bevel the end of a pipe. The Reed bevel blade is a cylindrical wedge-shaped body which has a plurality of integral teeth. This bevel blade may be used to create a beveled edge. However, if a tooth dulls or breaks, the bevel blade becomes ineffective or useless. The blade must then be returned to a machine shop for any type of repair or maintenance. Such maintenance and repair, therefore, is both time consuming and costly.
U.S. Pat. No. 4,689,883 to Dent discloses a hand held saw for simultaneously cutting and beveling plastic pipe. The Dent saw simultaneously cuts a pipe to the proper length and bevels the ends of both pieces formed by the cutting process. This dual beveling is accomplished by a blade system comprised of a mounting block with slots adapted to accommodate the thick end of at least one cutting blade. The Dent cutting blades are secured by a system of shim plates and set screws. Each cutting blade has two cutting surfaces that form an obtuse angle. A narrowly protruding section separates the two cutting surfaces. The cutting surfaces of the cutting blade extend beyond the mounting block and are subject to breakage. The center portion of the blade, where the two cutting surfaces and the protruding section are located, are particularly susceptible to this breakage. Once broken, the entire cutting blade must be replaced. Another problem is that the Dent saw is limited to cutting beveled edges on both pipe edges. This limits the use of the pipe to those uses associated with beveled edges. Further, dual beveling wastes time and energy when the second, remaining portion of pipe is too short for use. Finally, even if the second portion of pipe is usable, the bevel might be marred if it is not used right away. Other problems with the Dent saw include instability, exposed teeth, spin direction, and other problems that might prevent it from complying with safety regulations.